Hey there! :D
All parallel lines have the same slope. They would need to, otherwise, they would intersect or come together at an angle eventually.
So, let's find the slope.
I'm going to use rise over run. (Remember, when moving to the left, you make the number negative.
rise=1 run= -3
-1/3 <== the slope
"C" is the correct answer.
I hope this helps!
~kaikers
